1. Field of the Invention
The present invention relates to a high voltage transformer for controlling inductance leakage. In particular, this invention changes the shape of the magnetic unit located at the outside of the wire frame to control loss due to the transformer being switched between high voltage and low voltage. Thereby, the magnetic flux is lowered, the inductance leakage of the transformer is controlled and the dimensions of the transformer are acceptable.
2. Description of the Related Art
LCD monitors and LCD TVs are commonly owned apparatuses today. They are also applied in industry, such as tools for monitoring, operating, and advertising. LCD monitors and LVD TVs use a multiple lamp driving system that is composed of CCFLs and driving transformers as a backlight. Therefore, the endurance and the stability of the transformer are the key factors of the product yield rate.
FIG. 1 shows a transformer of the prior art. The transformer has a wire frame a. There is a receiving space a1 in the wire frame a for receiving a first magnetic unit b. The surface of the wire frame a is separated into a first region a2 and a second region a3. A first winding c and a second winding d are individually wound at the first region a2 and the second region a3 of the wire frame a. An inverted U-shaped second magnetic unit e is covered on the side of the wire frame a.
The described transformer has the drawbacks:
1. The magnetic flux of the transformer is too high. Therefore, switching loss caused by switching the transformer between high voltage and low voltage cannot be controlled well. The switching loss caused by switching the transformer between high voltage and low voltage lowers the efficiency of the magnetic unit so that the transformer has an overheating problem. In order to exhaust the heat, the dimension of the transformer becomes larger so that the transformer occupies a larger space.
2. The magnetic unit of the prior transformer cannot control the inductance leakage. So, it does not fit in with the requirements of LCD monitors or LCD TVs.
3. In order to achieve a good visual effect for LCD monitors or LCD TVs, the number of the lamps is increased. The prior transformer cannot drive a plurality of lamps via a high voltage transformer.